Flushing a tool for closed well operation and an associated method

Abstract

A closed operation subsea well tool assembly with a flushing system flushing a first fluid in the main bore (15) of the tool assembly (1). The flushing system of the tool assembly comprises a container (19) with a second fluid, a pump (2), a swab valve (20) in the top of the main bore (15), an inlet (3) in the bottom of the main bore of the tool assembly, which is connected to the pump. Outlet(s) (5a, 6a) are below the swab valve, configured to guide out the first fluid from the main bore. A fluid channel (7) extends from the outlet (5a, 6a) and down to channels of the wellhead module (10) or the wellhead (31). Methods using the tool assembly are also disclosed.

Description

[0001]The invention relates to a fluid circulation system for use in a tool that makes mechanical and / or pump operations possible in subsea wells or wellheads, without the use of wire or coiled tubing up to the rig, ship or platform. In particular, the present invention relates to flushing of an enclosed cavity which may contain a well tool arranged in a well liquid environment, without the well barriers for well control being penetrated or containing fluid inflow to the operation vessel, so that flushing is performed without exposure or return of hydrocarbons to the vessel. It is also vital that the invention avoids high pressure well liquid, such as hydrocarbons, back to the operation vessel, so that a more plain ship can be used for the desired well operation.BACKGROUND OF THE INVENTION[0002]The background of the invention is the need in the petroleum industry for cost reducing subsea operation with an equal or higher level of safety, compared to the present practice. It is commo...

AI Technical Summary

Problems solved by technology

It is commonly known that developing and operating a subsea field that typically has multiple wells with associated Xmas trees requires a large investment both in equipment and operational costs.

A large portion of the cost for such a development stems from the drilling, completion, startup and service of the wells.

Common for such operations and systems is that they involve large costs to manufacture, operate and maintain.

The heavy weight and the size of a workover system is also significant, as such a system includes many containers on deck, as well as large reels with umbilicals.

An example of this will be at loss of well control, where the main safety valves must be activated to shut in or isolate the well from the environment.

This will again result in significantly lighter equipment for maintaining well control.

Common for these solutions is that they will potentially expose the operation vessel to hydrocarbons—either directly by carrying along filled tanks or indirectly via leakages through attached umbilicals or pipes.

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